I have one even better:
poolhop prop pools, payout "feeless" PPS, submit to SMPPS or similar as backup
Yeah, that's another thing I've been thinking about for a while (even before Multipool did something similar), but
1. Why stop at feeless? You can offer above 100% PPS while still maintaining a large profit margin.
2. With enough proportional pools there's not much need for backup, but for a backup you'll probably want to use a hopping-proof pool rather than SMPPS.
3. This is of course more controversial than a non-hopping proxy.